In textile machines producing cross-wound bobbins, for example open-end spinning machines or winding machines, yarns are wound onto empty bobbin tubes to form cross-wound bobbins. In the development of cross-wound bobbins, the yarns are generally drawn off overhead. In order to prevent the yarn becoming caught or rubbing on the edge of the tube while being drawn off, the tube is beaded on the tube tip toward the withdrawal end of the tube. Furthermore, a peripheral groove for depositing a foot reserve may be provided on the tube foot at the opposite end of the tube. A groove of this type is also called a yarn reserve channel. It emerges from the aforementioned configuration of the bobbin tube that correct orientation of the bobbin tube is necessary in the production of the cross-wound bobbin.
It is known that textile machines producing cross-wound bobbins are equipped with tube magazines, from which the tubes can be transported in an automated manner to the workstations of the textile machine. These tube magazines are loaded manually by an operator. The operator has to place the bobbin tubes with correct orientation on mandrels of the tube magazine.
The constant aim is to automate work sequences on textile machines producing cross-wound bobbins. Bobbin tubes may, for example, be automatically conveyed from a bulk goods container. In this case, the bobbin tubes are transported from the container with a random orientation. To further process the bobbin tubes, it is absolutely necessary to determine the orientation of each bobbin tube followed by a corresponding alignment of the tube.
German Patent Document DE 43 41 946 A1, discloses a mechanism for transporting the bobbin tubes within a textile machine producing cross-wound bobbins, including a mechanical sensor mechanism for determining the orientation of a bobbin tube, which is configured as described above. This sensor mechanism is configured as a tube sensing device which scans the tube ends and responds to the beading of a tube. Mechanical mechanisms of this type are expensive, susceptible to faults and require maintenance.
German Patent Document DE-OS 24 12 821 discloses a device for automatically supplying and properly aligning bobbin tubes. In order to be able to determine the orientation of the bobbin tubes, the bobbin tubes are marked on the end faces by labelling, printing, dyeing or the like. A photoelectric reflex light barrier is directed at the end face of a bobbin tube passing by. The reflex light barrier responds to the markings, in this case. It irradiates the end face with light and measures the reflected light quantity. The light quantity is changed by the marking. The production of the markings means a considerable outlay of expense. This method has therefore not proven successful.
German Patent Document DE 198 40 299 A1 discloses a device for recognizing the orientation of cops. An optical scanning device is also described here. The fact that the foot of the spinning cops has a larger diameter than the tip of the spinning cop is utilized in that the shading perpendicular to the spinning cop axis is measured at the spinning cop ends. A measuring arrangement of this type is inapplicable for cylindrical bobbin tubes.